1. Field of the Invention
This invention relates to the field of computers. More particularly, this invention relates to mechanisms for the updating of computer files
2. Description of the Prior Art
A problem in the field of computing is the requirement for regular updating of computer files (possibly by downloading a complete new version of the file or by an incremental update in which modifying data for modifying the existing file to form the updated version is downloaded) held on many different computers. A software update may be required because the program has altered in response to the occurrence of bugs within the program or to add additional functionality to a program. Another need for frequent computer file updates is when the computer file represents rapidly evolving data needed by the computer. An example of this is the computer virus definitions data that is used by many anti-virus computer programs. This computer virus definition data is typically updated when a new virus is encountered such that the anti-virus software may provide counter-measures to the new virus. In order that the anti-virus software being used may operate in an effective manner it is important that it should use the most up to date virus definition data.
In response to this need, anti-virus software suppliers often provide download facilities from which users can download the most up to date versions of the computer virus definition data. One problem with this approach is that a user must know that an updated virus definition data file is present in order that it should be downloaded. One way to deal with this is to configure the computer program software to automatically check for new computer virus definition data at periodic intervals. If these intervals are made too short, then this presents an unnecessary burden upon the computer systems involved. Conversely, if the intervals are made too large, then a significant update required to deal with a new virus threat may not be downloaded in sufficient time to adequately protect from that virus threat.
A further problem associated with the downloading of virus definition data from the anti-virus software supplier is that peak demand for the download of the new data may cause the systems to malfunction. Computer viruses are becoming increasingly common and destructive. With this background, the release of a new computer virus attracts considerable media attention resulting in many users simultaneously trying to download the updated data in a manner that causes this process to fail.
Various techniques for updating software are disclosed in U.S. Pat. No. 5,940,074, U.S. Pat. No. 4,763,271, U.S. Pat. No. 5,919,247, U.S. Pat. No. 5,577,244, U.S. Pat. No. 5,809,287, U.S. Pat. No. 5,933,647 and U.S. Pat. No. 5,732,275. A technique for updating anti-virus DAT files via a “push” method is disclosed in U.S. Pat. No. 6,035,423.
With conventional “pull” techniques for updating computer files the provider of the updated computer file has relatively little control over the download demand. In critical situations the resources of the provider to enable download by remote computers may be overwhelmed resulting in denial of download to some users. It may be that in these circumstances download of an updated computer file to highly critical corporate mail servers, firewalls and file servers would be denied whereas download to a relatively unexposed home user would be granted.